1. Field of the Invention
This invention relates to a thermosensitive image transfer recording medium, and more particularly to a multicolor thermosensitive image transfer recording medium for high-speed printing.
2. Discussion of Background
In general, thermofusible ink layers commonly used for multicolor recording comprise as the main components non-crystalline wax or non-crystalline thermofusible resin and a coloring agent. Such conventional thermofusible ink layers have the shortcoming that satisfactorily clear-cut sharp images cannot be obtained at high speed printing, for instance, of 50 characters per second (cps) or more. Furthermore these thermofusible ink layers have the shortcoming that unheated portions thereof are transferred together with heated portions to a receiving sheet.
In order to improve the sharpness of reproduced images and to prevent the occurrence of the problem of the transfer of unheated portions to a receiving sheet, it has been proposed to add fillers to such a thermofusible ink layer. By the addition of fillers to the thermofusible ink layer, the occurrence of the transfer of the unheated portion of the ink layer to a receiving sheet can be reduced to some extent, but most of available fillers such as silica and alumina have a refractive index of 1.65 to 1.75 and cover the color of coloring agents when used in combination with the conventionally employed thermofusible waxes or resins in the thermofusible ink layers, so that when such fillers are employed in a thermofusible ink layer, images produced from such a thermofusible ink layer are dark and dull, in particular when projected by an overhead projector (OHP), and when multicolor images are formed by overlapping thermofusible ink layers with different colors.